1. Field of the Invention
This invention relates to a circuit breaker operating apparatus, or more in particular to a circuit breaker operating apparatus suitable for high-speed operation of a large-capacity circuit breaker.
2. Description of the Prior Art
With the recent increase in the demand for electric power, there are more and more installations of high power transmission line circuit network, any breakdown of which is liable to lead to an extensive power failure. In order to minimize the effect of such an accident, the point of breakdown is required to be isolated from the rest of the circuit network immediately. This requires high-speed breaking operation of a circuit breaker provided in the network.
If the circuit breaker is required to operate at high speed, its operating apparatus must be also actuated at high speed.
A conventional high-speed circuit breaker has such an operating apparatus that an operating medium such as compressed air is used to obtain operating force for either breaking or closing operation, and the restitutive force of a spring stored during such an operation is utilized to derive force of other operation. For simplicity's sake, the description below assumes an arrangement in which the operating and closing forces are derived from an operating medium and a spring respectively. In an apparatus in which, after the operating medium acts on the operating piston connected to an operating member for operating the breaking section the circuit-broken condition is maintained by the operating medium, it is necessary to release the operating medium acting on the operating piston at the time of closing the circuit breaker, making it difficult to perform the closing operation at high speed. Further, in the event that the operating medium is reduced in pressure for some reason or other, the apparatus cannot maintain the circuit-broken condition and is liable to be undesirable closed state.
To improve this situation, another conventional circuit breaker operating apparatus has been proposed in which the circuit-broken state is maintained mechanically by holding means at the time when the breaking operation is completed and at the same time all the operating medium acting on the operating piston is exhaused so that the operating medium can not act to prevent the closing operation when the circuit breaker is closed next. This conventional apparatus makes possible a high-speed breaking and closing operation. However, the disadvantages of such improved conventional apparatus are in that the holding means for holding a large mechanical operating force is considerably bulky and hence the arrangement of such holding means at a position facilitating its own installation and inspection is difficult at the time of installation.